As imaging techniques using X-ray CT (Computed Tomography) apparatuses, there are known, for example, an imaging technique called “jog shuttle scanning” and an imaging technique called “helical shuttle scanning”.
Jog shuttle scanning is configured to sequentially repeat moving and stopping a bed for each slice and execute X-ray imaging at the time of the stoppage of the bed. This can reduce artifacts but prolongs the imaging time.
Helical shuttle scanning is configured to irradiate an object with X-rays in a helical pattern by continuously and reciprocatingly moving a top while continuously rotating an X-ray tube on a circular orbit centered on the object. This can obtain a tomographic image of the object, covering a wide range and having excellent continuity.
In X-ray imaging using jog shuttle scanning and helical shuttle scanning, the bed on which an object is placed is driven to obtain data of a wide region. Along with this movement of the bed, the relative positional relationship between the object placed on the bed and the bed changes. In other words, the position of the object shifts relative to the bed along with the driving of the bed.
In this case, although the X-ray CT apparatus side is grasping the transition of the position of the bed itself, it cannot grasp the transition of the position of the object on the bed (a change in the relative position between the bed and the object). That is, in the reconstruction of projection data, consideration is given to only the transition of the position of the bed itself.
As a consequence, the reconstructed image obtained by reconstructing projection data reflects the positional shift of the object relative to the bed (a change in the relative position between the bed and the object). This may cause, for example, artifacts and the like and degrade the accuracy and reliability of the reconstructed image.